The present invention relates to a device that is able to evaluate the exercise capacity and exercise fitness of a living organism. More particularly, it relates to a muscular strength estimation device that is able to estimate muscular strength by measuring oxygen saturation or the like with simple means using non-invasive optical technology.
Methods that have been used to evaluate muscular exercise capacity and exercise fitness have included invasive methods such as removing muscular tissue, blood analysis by inserting a catheter, and measuring the amount of lactic acid in a small amount of blood obtained by pricking the subject""s finger with a needle. However, in recent years it has become possible to use optical technology to measure muscular exercise capacity and exercise fitness non-invasively in real-time with a device that measures the oxygen concentration in the blood circulating through the muscles.
In Japanese Patent Application Laid-open No.H6-142086 an exercise monitoring device is disclosed which uses optical technology to measure the change in the oxygen concentration in the blood circulating through the muscles and determines the subject""s maximum exercise tolerance and oxygen uptake. This exercise monitoring device detects the point of inflection in the oxygen concentration in the blood based on the change in the oxygen concentration while the subject is exercising, and determines the subject""s maximum exercise tolerance and maximum oxygen uptake based on the exercise tolerance level reached by the subject at the point of inflection.
However, no device yet exists that uses optical technology to measure muscular strength. The force that muscles actually exert is not the same as that which we subjectively perceive and differs from the force that we estimate sensorily. Previously therefore, conducting physical training while estimating muscular capacity scientifically and with certainty imposed a heavy burden on the subject, since major, invasive devices had to be used. This has led to an increase in demand for the development of a device that makes it possible to conduct training non-invasively and scientifically, and devices that use optical technology have begun to attract attention.
One way to estimate the force exerted by muscles using optical technology is to measure the oxygen concentration in the blood circulating through the muscles. Parameters that represent the oxygen concentration in the blood include HbO2, Hb, t-Hb, and SO2, but t-Hb changes according to exercise intensity, at the sane time affecting HbO2 and Hb. Therefore it is impossible to accurately monitor the change in oxygen concentration with these parameters. On the other hand, SO2 (oxygen saturation) is not affected by a change in exercise intensity, and since it changes in response to the degree of muscular exercise, by detecting oxygen saturation it is possible to estimate the force exerted by the muscles.
Therefore, an object of the present invention is to provide a muscular strength estimation device that non-invasively detects oxygen saturation (SO2) in the blood circulating through the muscles using optical technology, making it possible to conduct scientific training while matching subjective perception with muscular strength.
In order to solve the above-mentioned problems, a muscular strength estimation device according to the present invention is a device for estimating muscular strength, comprising: load supply means for applying a prescribed exercise load to a subject; oxygen saturation measuring means for measuring, while the exercise load is being applied to the subject, oxygen saturation in the blood circulating through the muscle to which the exercise load is applied; minimum value detection means for detecting the oxygen saturation minimum value during measurement; recording means for recording in advance a correlation table showing the correlation between the subject""s oxygen saturation and muscular strength; and calculation means for calculating the muscular strength corresponding to the oxygen saturation minimum value, from the correlation table. According to the present invention, it is possible to estimate a subject""s muscular strength in real-time by a non-invasive method using a simple device.
In addition, a muscular strength estimation device according to the present invention is a device for measuring muscular strength, comprising: load supply means for applying a prescribed exercise load to a subject; oxygen saturation measuring means for measuring, while the exercise load is being applied to the subject, the oxygen saturation in the blood circulating through the muscle to which the exercise load is applied; minimum value detection means for detecting the oxygen saturation minimum value during measurement; recording means for recording in advance the minimum oxygen saturation when the subject was exerting maximum muscular strength; and calculation means for calculating the muscular strength when a prescribed exercise load is applied to the subject, using the subject""s oxygen saturation before the exercise load is applied to the subject, the oxygen saturation minimum value that was detected and the minimum oxygen saturation when the subject exerted maximum muscular strength. According to the present invention, it is thus possible to calculate the subject""s muscular strength even without correlation table between oxygen saturation and muscular strength.